(a). Field of the Invention
The invention relates to amplifying circuits, and more particularly to a linearity improved amplifying circuit and an associated linearity improving method.
(b). Description of the Prior Arts
In some circuits, high linearity amplifiers are needed. For example, in wireless communication systems such as 802.11a/b/g, the amplitude modulation (AM) needs high linearity power amplifiers to avoid signal distortion resulted from signal transmission. However, the amplifier such as the transistor amplifier usually has a non-linear input capacitor whose capacitance value varies with the input power of the amplifier. This would cause the AM to PM distortion of the amplifier to degrade the linearity of the amplifier.